Liquid crystal display devices are thin, have low power consumption, and are widely used in various fields. In particular, liquid crystal display devices with active matrix liquid crystal panels having a switching element such as a TFT (thin film transistor) for each pixel have high contrast display and excellent response characteristics, and are widely used for televisions, monitors, and the like.
Main components of conventional liquid crystal panels include a pair of glass substrates, a liquid crystal layer between these substrates, electrodes on each of these glass substrates, and a polarizing plate attached to each glass substrate.
In this type of liquid crystal panel, the light emitted from the backlight passes through the polarizing plate and the liquid crystal layer and facilitates display of an image due to the contrast on the screen.
However, some of the light entering the liquid crystal panel from a backlight is absorbed or reflected as it passes through the liquid crystal panel. In particular, as mentioned above, in order to control the transmission of light, a liquid crystal panel is provided with polarizing plates, which allow through only components polarized in specific directions, on respective surfaces of the pair of substrates opposite to the surfaces facing the liquid crystal layer. Thus, only a portion of the light that enters the liquid crystal panel passes through the polarizing plates with a large portion of the light being absorbed by the polarizing plates. The loss of light due to absorption by the polarizing plates is a major factor in the decrease of light usage rate.
Thus, recently, display panels that do not need polarizing plates are being developed.
Patent Documents 1 and 2 disclose an optical device that contains polymer flakes suspended in a liquid medium, the polymer flakes being formed in a particular shape, size, and a prescribed color range, or being formed so as to have a space marking such as a protrusion or a dent, for example. The optical device can display the above-mentioned coded information and space markings at a particular color range or various spectrum characteristics by selectively switching the optical characteristics thereof by altering the electric field applied.
Furthermore, Patent Document 3 discloses a transflective display in which voltage is applied to a suspended insulating fluid such as platelet-shaped metal particles, for example, in order to orient the metal particles in a vertical or horizontal direction such that the metal particles transmit and reflect light that has entered the suspended insulating fluid (particle suspension).
In this manner, a display using flakes such as polymer flakes and platelet-shaped metal particles (hereinafter, flake display) can perform display with excellent contrast due to light reflection and absorption, and because a polarizing plate is not used, the light usage efficiency can be improved compared to liquid crystal panels.